Floor polishes generally are sold as an aqueous emulsion vehicle composition, whereby volatilization of the aqueous component of the emulsion causes a dispersed polymer component to form a film that is the resulting polish. However, the polish typically must have physical properties that are distinct from those of the polymer component of the emulsion. For example, following evaporation of the aqueous component of the emulsion, the resulting polish film should present an even appearance, exhibit resistance to physical impact and be relatively inert to the presence of water.
One attempt to impart the necessary physical properties to floor polishes has been the inclusion of a chemical component in the emulsion that reacts with the polymer during volatilization of the aqueous phase. For example, use of a multivalent transition metal, such as zinc, in the aqueous phase, can cause cross-linking of the polymer component consequent to the reaction of the multivalent transition metal and carboxyl groups while the polish dries. Cross-linking by the multivalent transition metal causes the resulting polymer film to be harder and exhibit greater water resistance.
However, an excessive amount of multivalent transition metal can cause premature coagulation and precipitation of the dispersed polymer and metal components. As a result, the emulsion can be difficult to spread properly or exhibit poor drying, and can cause the polish to exhibit an uneven appearance. Therefore, the utility of multivalent transition metals to improve the quality of floor polishes has been limited.
An attempt to increase the amount of multivalent transition metal that generally can be employed has included use of a nonionic surfactant. A secondary outer layer on the dispersed polymeric particles is formed by the nonionic surfactant, thereby improving product stability in the aqueous phase. Use of a nonionic surfactant has typically enabled a stoichiometric ratio of transition metal to the available reactive groups of the polymers, e.g. carboxyl groups, of up to about 1:2. See, for example, U.S. Pat. No. 3,308,078, issued to J. R. Rogers et al. on Mar. 7, 1967.
In another attempt, such as described in U.S. Pat. No. 4,517,330, issued to Zdanowski et al. on May 14, 1985, the basic salt of an alkaline metal, such as sodium or potassium, has been employed. The alkaline metal further improves the stability of the polymer, thereby enabling up to a stoichiometric equivalence of transition metal without premature coagulation. However, the alkali metal does not dissipate during evaporation of the aqueous phase. Consequently, the alkali metal remains in the polymer film and often causes the polish to be brittle and to exhibit diminished resistance to water.
Therefore, a need exists to overcome or minimize the above-referenced problems associated with floor polish vehicle compositions.